With increasing concern for the environment, there is an increasing need for sources of energy which do not cause pollution, for example the harvesting of wind energy. Use of wind turbines to produce energy by driving a generator is known, however known systems typically require large costly turbines to be supported on large towers which are generally costly to install. Furthermore effective designs of turbines for harvesting wind energy on a large scale are generally considered to be visually unappealing in an urban environment.